The number of measures of wheat was considerably less than Solomon’s own annual consumption, which exceeded 32,000 cors 1 Kings 4:22; but the small amount of twenty cors of oil, which seems at first sight scarcely to match with the 20,000 cors of wheat, will not appear improbable, if we consider that the oil was to be” pure” - literally “beaten” - i. e., oil extracted from the olives by pounding, and not by means of the press.
Year by year - i. e., during all the years that Solomon was engaged in building and was helped by Hiram.